The invention relates to a self-jamming descender with two jamming positions for a user to descend along a rope, and comprising :
a first base flange, equipped with a first fixed pulley offset with respect to an articulation spindle, perpendicular to the first flange, PA1 a second pulley securedly united to a mobile support plate, pivotally mounted around the spindle in a parallel plane to the base flange, PA1 an operating handle secured to the support plate and second pulley assembly to form a jamming device with two jamming positions of the rope, which is wound in an S in the guide grooves of the two pulleys, unjamming taking place in an intermediate position of the operating lever, PA1 a second flange parallel to the first base flange with the two pulleys being interposed in a transverse gap, said second flange being retractable to allow the rope to be wound on the pulleys, PA1 attachment means of the two flanges to a harness, PA1 and a first braking surface arranged on the first fixed pulley against which the rope is pressed by a boss of the second pulley in a first jamming position of the operating lever.
A descender of this kind is known from the document FR-2,451,752 in which the second pulley is equipped with two bosses cooperating with the first pulley to form a jammer with two jamming positions, when the pivoting operating lever is alternately in two extreme positions. It can be noted that the jamming function of each boss is always exerted on the same intermediate strand of the rope, arranged between the two pulleys. The movement of the operating lever between the two jamming positions is in the order of a quarter-circle, and the manual unjamming action to the intermediate position of the operating lever requires great effort.